This invention relates to a pneumatic exerciser having a double-acting pneumatic cylinder which can be adjusted to provide a selected resistance in either the tension or compression mode of operation.
Various types of exercise equipment have been developed for muscle building and toning, whether ultimately used as a sport or for physical therapy. One of the more common types of exercise equipment is the weight type device which uses weights to provide the necessary resistance. As is well known, these weight type devices have several disadvantages. They are cumbersome to move since they are generally associated with a frame and bench assembly and the weights need to be moved when the equipment is moved. In addition, these devices may cause injury to an inexperienced user since the weights may be dropped suddenly. Further, when weights are lifted an inertia of movement is created which tends to provide unevenness in the operating resistance during the exercising process.
To overcome these deficiencies various hydraulic systems have been developed such as described in U.S. Pat. No. 4,444,390 to Erichson; U.S. Pat. No. 4,629,185 to Amann; U.S. Pat. No. 4,465,274 to Davenport; and U.S. Pat. No. 4,429,871 to Fleschner. Most of these hydraulic devices use a frame or bench assembly to which the apparatus is mounted, and as a result thereof, this equipment is also not easily transportable. Further, these devices have the disadvantage of requiring somewhat complicated setup procedures before a person can exercise a particular muscle group. This is a problem for physical therapists who want to have equipment which is easily transportable from the office to a patient's home and which equipment can be easily used by the patient without the necessity of providing expensive accessory equipment.
Portable hydraulic exercisers are known. For example, see U.S. Pat. No. 3,834,696 to Spector. This device includes two telescoping tubes which have handles attached to the ends thereof. However, with the general type of device described in this patent, the user must grasp the two handles and either push the two handles together or pull the two handles apart. Thus, this device has limited utility in exercising other muscle groups.
Further, pneumatic systems have also been developed to overcome the disadvantages of weight type systems and the disadvantages of the hydraulic systems. A hydraulic system PG,4 is a "hard" system since fluid is not compressible. On the other hand, a pneumatic system is a much "softer" system since air is compressible to a certain degree. Examples of pneumatic exercise equipment would include U.S. Pat. No. 4,257,593 to Kelser (utilizing a source of compressed air to provide resistance) and U.S. Pat. No. 3,471,145 to Berger.
In the known hydraulic and pneumatic devices, there are none which show closed systems which permit control of the resistance to be encountered during the compression stroke and the tension stroke independently of one another. Further, none disclose a gauge for determining the amount of resistance being encountered when muscular force is exerted during both the compression or tension stroke.
U.S. Pat. No. 4,465,274 to Davenport does describe a double acting hydraulic cylinder where hydraulic fluid is directed through an external line from a chamber on one side of the internal hydraulic piston to a chamber on the other side of this piston. An adjustable valve is provided in this external line to provide restricted flow in both directions at the same time. This valve does not permit independent control of the resistance in the compression stroke and the tension stroke. A pressure gauge is used to indicate the hydraulic pressure within the line during fluid flow in one direction but not both directions. This exerciser is used by exerting muscular force on the piston and moving the piston against the hydraulic pressure developed by forcing fluid through the valved external line.
U.S. Pat. No. 3,471,145 to Berger describes a telescoping tube pneumatic exerciser. Here the end wall of one of the telescoping tubes acts as a pneumatic piston. In this device, the flow of air between the two tubes may be adjustably restricted by flap valves located on the piston element of this device. This patent describes structure for selecting the resistance to be encountered in either the compression or the tension mode but not both. This patent also describes a portable exerciser but again uses handles which are mounted at each end of the exerciser. The handles are grasped and are either pulled toward one another or pulled apart.
In view of the exercise apparatus now known, there is a need for a device where a user can adjust the tension resistance and compression resistance independently of one another. There is a need for a device which is transportable and which can be set up in a person's home easily without requiring a complicated bench and frame assembly. Further, there is a need for a device which is versatile in being able to exercise many muscle groups without having to go through extended setup procedures.